The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Frame => Topic started by: Greybeard on 13.03. 2018 15:58

Title: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: Greybeard on 13.03. 2018 15:58
Quote from: fixit58 on 13.03. 2018 15:08
believe it or not but ALL the brake components are BRAND NEW. It's the mismatch of brake cable length and operating lever that I have to redo. works superbly in spite of that.
I beg to differ. The operating arm needs ideally to come to 90° when the brake is applied. When that brake is applied it will be well past the best leverage.
Title: Re: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: A10 JWO on 13.03. 2018 16:36
Looks like my brake arm on the signature photograph before the repair.
Title: Re: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: Greybeard on 13.03. 2018 17:16
Quote from: A10 JWO on 13.03. 2018 16:36
Looks like my brake arm on the signature photograph before the repair.
Maybe. My eyes are not that good!
Title: Re: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: Topdad on 14.03. 2018 16:42
After say my front (8" single sided ) is getting very close to max adjustment (adjusters at h/bar and wheel ) but the arm is still in the right position was still working well  methinks  I'll look into a new cable first
Title: Re: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: Butch (cb) on 15.03. 2018 17:23
Need to watch it won't go 'over cam' I guess.
Title: Re: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: Greybeard on 15.03. 2018 17:50
Quote from: cyclobutch on 15.03. 2018 17:23
Need to watch it won't go 'over cam' I guess.
I think it's more that you are reducing the leverage that is applied to the brake. The term 'Moment Arm' is at the back of my mind. It must be just as bad if the lever was too much the other way. Obviously 90° when brake is applied gives best result; same with the clutch lever on the gearbox.
Title: Re: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: a10 gf on 15.03. 2018 19:33
Quote from: cyclobutch on 15.03. 2018 17:23
Need to watch it won't go 'over cam' I guess.

That should be impossible... cam will surely (maybe? :O) not have clearance to 'go over' even with shoes down to bare metal, that said there may be worn out \ defective \ non-original parts in use, so always be safe and check everything.

As for the angle, I think Greybeard is very right.
Title: Re: Brake arm angle (topic extracted from 'A10 chinese speedo')
Post by: Butch (cb) on 16.03. 2018 08:44
Quote from: a10gf on 15.03. 2018 19:33
Quote from: cyclobutch on 15.03. 2018 17:23
Need to watch it won't go 'over cam' I guess.

That should be impossible... cam will surely (maybe? :O) not have clearance to 'go over' even with shoes down to bare metal, that said there may be worn out \ defective \ non-original parts in use, so always be safe and check everything.

As for the angle, I think Greybeard is very right.

Don't know about an A10, I managed it on a little 250RS I was running on the cheap. I'd 'readjusted' the brake arm in accordance with GB rules to maintain efficiency, but as the cam gets to full extent it locks the brake on. Eeek said both the rear tyre and I.